Cylinder Metallurgy and Wall Thickness Considerations

[raymon covey]

This is an interesting subject. After many. years of 88, "90.5, and 92's I have dabbeled in the 94's I have found that many are undesirably thin in the stud area. It seems that on the late aa's that one cylinder in each set is very thin in the stud area. This forces me to boy more than one set and pick the thickest in that area for performance engines. This was brought on by examining used cylinders and finding these are the highest in warpage of the set. This has helped some but it would be nice is AA would get its act together and make some cylinders for 8 mm stud only application. In addition to staying straight the cylinders would carry more heat to the bottom to be dissipated through the oil and may result in lower temps. Just my thoughts. I have had one failure of a cylinder blowing through the side of the cylinder in this area. The wall thickness was .040. Many of them run quite thin in that area.

[jpaull]

[BigO_Oh]

Revmaster's long (cut-to-length) 94mm cylinders are thicker than most. The set I got was a bit too tight with 10mm studs, requiring some filing, mostly at the base, otherwise they would resist fully seating, cold.

They needed honing too - quite rough out of the box. They had the typical casting flash at the seam.

Jaycee used to sell them (may still?), but I ordered directly from revmaster and were kind enough to drop them off at nearby Brothers, with the request to cut them down for 0.040" deck height, since they were doing hoover mods on a TF1 case anyway. It was the first TF1 Brothers had in-house - 2015, if I recall correctly.

Once everything arrived home, was cleaned up and assembled, deck height measured at 0.045". Close enough.

I hope Revmaster will keep making 'em. If not, I guess it'll be JPM for their ultra premium (thick) iron cylinders. JPM's are pricey enough, but I'm not paying thousands for LN nikasil, as much as I'd appreciate the cooling properties.

[TXHCBeetle]

I've been reaching out to various sources for data.
Mahle & AA cylinders have a Brinnel Hardness of around 200 Hb, RevMasters are around 265 Hb. JPM's are harder than Mahle/AA, but I dont have a hardness value for them. JPM cylinders only accept 8mm studs, so they are the thickest 94's in the stud relief area, and they use the same cast iron formula as Volvo Heavy Equipment
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[KEGZ]

You guys are spot on. I brought my Revmaster long cylinders to brother's to be drilled for the extra studs in an AA box and they immediately expressed concern about warpage. I got the same reaction from VWP in the same box. They were relieved to see they were Revmasters and that I had only been using the box.

[catbox]

I purchased a set of Revmaster long cylinders back in 2012.
Here is what I have found out as I fiddled with them when I was building an engine for my bug.

Revmaster Website Photos

This is a fresh from the box photo after I had JayCee cut them to length for my 2332 project.

Here are a few of my observations:

You can see that they are thicker at the top than the Mahle 94mm "A" cylinders that I replaced them with.

As measured before I sent them to the machine shop to be cut down to fit into the head properly.

Revmaster on the left and a Mahle on the right.
There was no fitting the cylinder into the Steve Tims Stage 2 head.
Thus they were sent out to be made to fit my heads.

At the time I had a 10mm stud engine and to fit the cylinders down the studs all the way to the block, I had to do the same clearance modifications to both sets of cylinders. Easily done with a sanding roll on a dremel.

Here you can see the Revmasters on the left have one less full circle cooling fin on the top of the cylinder than the Mahle on the right. I am sure this equates to just about nothing in the long run though.

Lastly, there was a height difference in the top of the cylinder.
Here is the Mahle 94mm "A" cylinder measurement:

And the Revmaster measurement:

It was at this point that I could no longer support the financial side of all the different trips to the machine shop and I ended up shelving all the parts.
Then my buddies drag car destroyed its case, for him to be up and running right away I sold him my case. So all the parts are stored away safely having never been used.

Now I am saving for a case to begin building it again for my squareback....
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"...these cars were preferred by the racers because the strut front suspension results in far superior handling than the regular torsion bar front end..." - Keith Seume.

[TXHCBeetle]

[catbox]

Since I have purchased mine, they could very well have corrected the top of cylinder measurement. Who knows.

They look to be a nice product and I will be putting them into service one of these days.
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"...these cars were preferred by the racers because the strut front suspension results in far superior handling than the regular torsion bar front end..." - Keith Seume.